diff --git a/src/libslic3r/LayerRegion.cpp b/src/libslic3r/LayerRegion.cpp
index 3fc8d03d1..6fc0b4e37 100644
--- a/src/libslic3r/LayerRegion.cpp
+++ b/src/libslic3r/LayerRegion.cpp
@@ -365,26 +365,23 @@ void LayerRegion::prepare_fill_surfaces()
     
     // if no solid layers are requested, turn top/bottom surfaces to internal
     if (this->region()->config().top_solid_layers == 0) {
-        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface)
-            if (surface->surface_type == stTop)
-                surface->surface_type = (this->layer()->object()->config().infill_only_where_needed) ? 
-                    stInternalVoid : stInternal;
+        for (Surface &surface : this->fill_surfaces.surfaces)
+            if (surface.is_top())
+                surface.surface_type = this->layer()->object()->config().infill_only_where_needed ? stInternalVoid : stInternal;
     }
     if (this->region()->config().bottom_solid_layers == 0) {
-        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
-            if (surface->surface_type == stBottom || surface->surface_type == stBottomBridge)
-                surface->surface_type = stInternal;
-        }
+        for (Surface &surface : this->fill_surfaces.surfaces)
+            if (surface.is_bottom()) // (surface.surface_type == stBottom)
+                surface.surface_type = stInternal;
     }
-        
+
     // turn too small internal regions into solid regions according to the user setting
     if (this->region()->config().fill_density.value > 0) {
         // scaling an area requires two calls!
         double min_area = scale_(scale_(this->region()->config().solid_infill_below_area.value));
-        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
-            if (surface->surface_type == stInternal && surface->area() <= min_area)
-                surface->surface_type = stInternalSolid;
-        }
+        for (Surface &surface : this->fill_surfaces.surfaces)
+            if (surface.surface_type == stInternal && surface.area() <= min_area)
+                surface.surface_type = stInternalSolid;
     }
 
 #ifdef SLIC3R_DEBUG_SLICE_PROCESSING
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index c4cc5e31d..1ce00f269 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -2894,7 +2894,7 @@ void DynamicPrintConfig::normalize()
         {
             this->opt<ConfigOptionInt>("perimeters", true)->value       = 1;
             this->opt<ConfigOptionInt>("top_solid_layers", true)->value = 0;
-            this->opt<ConfigOptionPercent>("fill_density", true)->value  = 0;
+            this->opt<ConfigOptionPercent>("fill_density", true)->value = 0;
         }
     }
 }